Israeli Cassini Soldner

Israeli Cassini Soldner (Hebrew: רשת ישראל הישנה‎ Reshet Yisra'el Ha-Yeshana; ICS) is the old geographic coordinate system for Israel. The name is derived from the Cassini Soldner projection it uses and the fact that it is optimized for Israel. ICS has been mostly replaced by the new coordinate system Israeli Transverse Mercator (ITM), but still referenced by older books and navigation software.

A trig station sign near Ofakim
Geodesy

History

The Cassini Soldner projection was used by the British Mandate of Palestine, when it was called the Palestine grid. The Palestine grid reached as south as Beer-Sheba. To avoid the existence of negative coordinates in the southern Negev, the False Northing of ICS was increased by 1000000.[1] As a result, coordinates in the south of Israel are higher than 800000.

Examples

An ICS coordinate is generally given as a pair of two numbers (excluding any digits behind a decimal point which may be used in very precise surveying). The first number is always the Easting and the second is the Northing. The easting and northing are in metres from the false origin. The easting is always a 6 digit number while the northing has 6 or 7 digits.

The ICS coordinate for the Western Wall at Jerusalem is:

E 172249 m
N 1131586 m

The first figure is the easting and means that the location is 172,249 meters east from the false origin (along the X axis). The second figure is the northing and puts the location 1,131,586 meters north of the false origin (along the Y axis). Also notice how the easting in this example is indicated with an “E” and likewise an “N” for the northing. The fact that the coordinate is in meters is indicated by the lowercase m.

The table below shows the same coordinate in 3 different grids:

Grid Easting Northing
ICS (Israeli Cassini Soldner) 172249 1131586
ITM (Israeli Transverse Mercator) 222286 631556
UTM (Universal Transverse Mercator) 711563 518045

Grid parameters

The ICS coordinate system is defined by the following parameters:[2]

a(m): 6378300.789
1/f: 293.466
  • Main datum point values:
Latitude of origin (D-M-S): 31 44 2.748999999990644
Longitude of origin (D-M-S): 35 12 43.490000000012970
  • Main point grid values:
False Easting (m): 170251.5549999999
False Northing(m): 1126867.909
  • Grid scale factor: 1
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References
  1. Dov Gavish (2005). The Survey of Palestine under the British Mandate, 1920–1948. London and New York: RoutledgeCurzon. pp. 73–75. In order to avoid negative values, the British set the value of the zero line at 1,000
  2. Published by the Mapping Center of Israel (MAPI) in the official website

Sources
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